Median and Ulnar Nerves Traumatic Injuries Rehabilitation

Peripheral nerves are structures that suffer injuries similar to those seen in other tissues, resulting in important motor and sensory disabilities. It is estimated that the incidence of traumatic lesions is as high as 500.000 cases per year in some countries, where 2,8% of the patients become permanently disabled due to prolonged nerve regeneration time (Noble et al., 1998; Rodrígues et al., 2004)

Ulnar nerve injuries cause palsy and hypotrophy in intrinsic hand muscles, palmar and dorsal interosseous, ulnar fingers lumbricals, hypothenar eminency, thumb adutor and thumb flexor brevis profundus, which results in a deformity characterized as ulnar claw hand (Figure 1). A typical deformity at 5 th finger in hyperabduction can also be present what usually happens because of the imbalance between intrinsic and extrinsic muscles. Hypoesthesia or anesthesia can be present at the 4 th and 5 th fingers. In proximal lesions, the muscles ulnar carpi flexor and profundus flexor of 4 th and 5 th fingers are affected. The most incapacity in that case is the reduction in grip strength. This is mainly attributed to failure in fingers abduction, damaging circumduction of a object in the act of prehension. The inefficiency action of the adductor muscles of the thumb also hinders the pinch execution (Pereira et al., 2003).

Physical and functional assessment
Through standardized assessment and analysis of physical disability, therapists and surgeons seek to determine the quality of results after surgery or to schedule and monitor the rehabilitation process in any disease, such as a traumatic nerve injury or compression syndrome, for example, thereby allowing, comparisons between different groups of patients (Amadio, 2001;Gianini, 2007;. New protocols have been developed and validated regarding evaluation items related to symptoms, dysfunction, disability and quality of life related to a disease, based on the World Health Organization concept. (Padua et al., 2007).
An early accurate diagnosis in all peripheral nerve injury is essential to determine the prognosis and treatment plan, which could be surgical or conservative.
In some cases are necessary complementary exams like images searching for nerve structures pathological alterations. To evaluate only the anatomy of the nervous structures, www.intechopen.com sometimes resulting in false-negative or false-positive diagnosis. In order to have a more accurate diagnosis and obtain more reliable information about the location, severity and prognosis of peripheral nerve injury, is fundamental to perform an electroneuromyography exam. This exam is a type of electrodiagnostic that investigate the existence of any alterations in the motor unit or in its components.
The Semmes-Weinstein monofilaments (Figure 2) are objective and semi-quantitative measurement instruments for assessment the skin peripheral innervations. It is considered a test of sensory threshold that evaluate the group of slowly adapting fibers. It is easy to apply, providing the mapping of sensory dermatomes, and can be used with reliability and repeatability. Bell-Krotoski, 2011).
The two points discrimination test (2PD) (Figure 2) evaluates the density of reinnervation of large myelinated fibers of the skin receptors, through a pressure-specific sensory device (Aszmann & Dellon, 1998). This test correlates with nerve conduction velocity, although this depends on several factors such as age (Kaneko et al., 2005) and should be accompanied by a description of how the test was performed to quantify the tactile discrimination, in association of others tests (Jerosch-Herold, 2000;Jerosch-Herold, 2003;Lundborg & Rosén, 2004). The prehension and pinch muscle strength are evaluated using the Jamar ™ and Pinch Gauge ™ dynamometer. The nominal value of isometric force is measured in kilograms, and the examined limb position follows the norms established by the American Association of Hand Surgery and the American Association of Hand Therapists (Abdalla & Brandão, 2005). Manual muscle testing is also useful in motor nerve recovery evaluation (Macdermid, 2005). Nerve repair is a specific situation that needs a specific available scale relating activity and participation allied with motor, sensation and discomfort dysfunction (Macdermid, 2005). Rosén et al. (1996) in their study highlighted four aspects in the recovery of hand function after a nerve injury, the more effective tests and its correlation with function. Through the calculating of data collection from various evaluation items in median or ulnar nerve injury in adults, an index called Rosén Score was validated (Rosén, 2000. It comprises several items divided into three areas: sensory, motor and pain/discomfort. These are related to pain sensitivity, motor function, muscle strength, function and identification of shapes and textures.

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These include mapping of sensory threshold that is accomplished through the use of the technique of esthesiometry on key points of sensory dermatomes related to nerves evaluated. The assessment of tactile gnosis is made by the Weber Disk Discriminator ™ (D2P), the shape and texture identification through the STI-test ™ (Figure 4) (Rosén et al., 1998. For the motor area, maximal isometric grip and pinch of the fingers are evaluated with the use of isometric grip strength using the Jamar ™ and Pinch Gauge ™ and functional manual muscle test is applied for palmar abduction, radial abduction of the second digit and adduction and abduction fifth digit (Brandsma et al., 1995).
The pain and cold discomfort are analyzed using a specific scale. To evaluate the sensory integration and motor function are applied four issues from Sollerman test (Figure 4) www.intechopen.com (Sollerman & Ejeskär, 1995). Thus, through this index is possible to monitor the progress of each patient after a specific rehabilitation process.
The esthesiometry test and identification of texture and shape test (STI-test ™ ) have psychometric properties evaluated and quantified and are considered tests with standardized criteria (Rosén & Lundborg, 1998;Jerosch-Herold, 2005).
The assessment of disability, progression, symptom relief and functional improvement due to disease or trauma remains a challenge. Several tools have been developed, either for dysfunction or for specific body segment analysis (Amadio, 2001, Heras-Palou et al., 2003Macdermid, 2002Macdermid, , 2011aMacdermid, , 2011b. The DASH questionnaire (Disabilities of the Arm, Shoulder and Hand) was developed in a multidisciplinary effort, based on questionnaires previously tested and is clinically useful for the entire upper limb in relation to their function. It is used for evaluation of single or multiple disorders. It is a disability questionnaire with 30 items related to activities of daily living, social integration, work and leisure. This questionnaire evaluates symptoms and physical function, with five response options for each item, totalizing 100 points. The higher the value, the greater the dysfunction (Beaton et al., 2001). This questionnaire is validated for several countries (Padua et al. 2003;Macdermid et al., 2004;Orfale et al., 2005;Themistocleous et al.,2006).
The evaluation process starts in the first visit but need to be repeated by times. It is crucial because can give the therapist the actual status of the regeneration process and prognosis but more than that, helps the therapist to educate the patient in a way he/she can understand what is happening and can occurs, give them a feedback, motivation and also a evidence bases for the therapist to change the treatment plan. It is a long rehabilitation period and the patient education is one of the keys for success and the focus must be in nerve regeneration process and brain interaction bringing the patient into his treatment and responsible for his rehabilitation.

Rehabilitation after peripheral nerve repair in the hand
The traumatic transection of median or ulnar nerve in the hand usually results in function impairment and represents a major problem for the patient. It can cause different levels of motor and sensitive dysfunction, as protective sensation, tactil discrimination, pain, disestesia, cold intolerance and uncoordinated grip strength. (Novak, 2001;Lundborg, 2000;Lundborg & Rosén, 2007). This kind of injury is common in the upper extremity of young male (Noble et al. , 1998).
The use of exercises post-immobilization period aim recover the motion and muscle function lost during the phase of immobilization. For example, with a low median and/or ulnar nerve repair, usually the wrist is positioned in flexion during the immobilization period and the patient may have restricted wrist flexion when permitted to begin exercises. Exercises are directed at gradually recovering of wrist extension and all fingers movement, generally starting with active range of motion (ROM). Passive and active-assisted ROM exercises are introduced depending on the patient´s progress as well as on specific precautions relevant to the individual cases.
In recovery phase, before an evidence of muscle reinnervation, passive exercises are important to maintain joint ROM and muscle-tendon length.
The motor retraining begins at the earliest evidence of muscle reinervation and progressive resistive exercise is also used to increase strength and endurance in muscle. Key exercises for median nerve injury involve the tenar intrinsic muscles and finger abduction an adduction exercises are key with ulnar nerve injury and also the intrinsic plus exercise.
The use of splints in peripheral-nerve injury to the hand, follow some principles like: to keep the denervated muscles from remaining in an overstreched position; to prevent a joint stiffness; the development of strong movement substitution patterns and to maximize functional use of the hand (Colditz, 2002).
The goal in splinting a low lesion of ulnar nerve is to prevent a overstretching of the denervated intrinsic muscles of ring and little fingers. Any splint that blocks the MP joints in slight flexion prevent de claw deformity by forcing the extrinsic extensor to transmit force into the dorsal hood mechanism of the finger ( Figure 5). High ulnar palsy lesions are commonly a result of trauma at or above de elbow and cause the palsy in flexor digitorum profundi associated with a absence of the all intrinsic muscles of the ring and little fingers. For this reason, clawing in the high ulnar nerve lesion is rarely present (Colditz, 2002). The deformity of the median nerve injury occurs with the flattening of the thenar eminence, with the thumb next to the palm of the hand, resulting in loss of opposition and palmar abduction. The goal of splinting is the maintenance of the first space, placing the thumb in palmar abduction and the indicator in opposition that could be indicated for night time (A) and promote function use of the hand during the day time (B) ( Figure 6). The number and type of regenerate nervous fibers as well the new connections after reparation or nerve reconstruction are quite different as original. The same stimuli will generate confusing sensorial impulses, sometimes painful or hard to interpret (Dellon, 1982(Dellon, , 1997. In consequence of axonal growth to other directions than original and due to remapping of cortical representation, the hand "talks another language to the brain", being necessary a time for sensory re-education in order to regain functional sensation as described, Dellon (1982) and Callahan (1990).
According to these programs the stimulation are started only when some return of sensitivity of the hand happens, usually several months after suture (Dellon, 1997). However, when evaluating recovery of tactile gnosis, which is the ability to discriminate objects, the result is disappointing Rosén & Lundborg, 2001). One reason for these bad results is the long absence of sensitivity that allows a disfunctional reorganization and change in the cortical map of the hand in the brain.
Sensory re-education is a process of reprogramming the brain trough a new learning process with progressive challenges, exploring the aid of vision trough exercises with opened and closed eyes. (Lundborg, 2000;Lundborg & Rosén, 2007). The proposed alternative sensory stimuli feed the somatosensory cortex and is essential to preserve the cortical map of the hand and to facilitate sensory recovery. .
Changes in cerebral cortex starts early after the lesion resulting in overlapping of adjacent cortical areas in response to absence of stimuli in injury nerve representation area. (Lundborg, 2000). In the early post-operative phase, mechanoreceptors in the hand, as well the cerebral cortex are intact, but functional properties of the communication system and peripheral nerve are lost (Lundborg, 1988). So, in case of absence of peripheral stimuli, a week is sufficient to alter neighboring cortical areas (Lundborg, 2000).
Several studies describe physiologic changes after peripheral nerve injury and its consequences in short and long term showed that relearning process is facilitated by sensory re-education programs (Lundborg, 2000;Dellon, 1982Dellon, , 1997Rosén & Lundborg, 2000).
Monkey experiments demonstrated that tasks executed by hands or even by the observation of other actions performed can activate pre-motor cortex neurons (Di Pellegrino et al, 1992;Di Pellegrino, Wise, 1993;Rizzolatti et al., 2001). Another study in humans through cortical image reveled that tactile hand stimulation activates areas of somatosensorial cortex (Hansson et al., 2004).
The observation of a tactile stimuli in the hand through mirror can hypothetically active neurons in somatosensorial cortex, so early re-education helps to preserve cortical representation and reduce or inhibit cortical "bad" reorganization that could occur without interventions (Lundborg & Richard, 2003;Merzenich & Jenkins, 1993;Pons et al., 1991;Buccino et al., 2004;Rizzolatti & Craighero, 2004;Rizzolatti et al., 1998). Rosén and Lundborg (1999), reports a case using the concept of artificial sensation based in substitution touch from hearing. They used a tactile glove with microphones over the fingertips which were introduced as the patient could move his hand, with five weeks postoperatively. The microphone captured the sound produced by the manipulation of objects and then was amplified for the patient to "hear" what the injury hand feels (Rosen & Lundborg, 2003). With the same goal of preserving the cortical map, case studies were performed with the use of mirror, which was established in the fourth week after surgery, replacing the visual stimulus by touch. A mirror was placed vertically in front of the patient to reflect the full innervated hand, thus the patient would receive the stimuli with the perception that the sensitivity of the damaged hand remains intact (Rosen & Lundborg, 2005).
Besides wide literature involving new rehabilitation and surgical concepts, there is still not a single technique that ensures the full recovery of tactile discrimination of the hand of an adult after a peripheral nerve injury (Lundborg & Rosén, 2007). Therefore, new strategies for sensory re-education could be adapted to the sensory and functional recovery after repair (Lundborg & Richard, 2003).
Methods such as the mirror and the sensory glove allow sensory reeducation is started early, before some innervation is noticed. Both studies showed favorable results for early realization of stimuli to keep the cortical areas and accelerate the return of sensitivity, although further investigations are needed with larger groups of individuals (Rosen & Lundborg, 2003, 2005.

Therapeutic modalities
The use of therapeutic modalities for peripheral nerve system regeneration is currently investigated. Low-power laser (Barbosa et al., 2010a(Barbosa et al., , 2010b), ultrasound (Monte Raso et al., 2005 and electric stimulation (Mendonça et al., 2003) have been used for accelerating regenerative processes in order to achieve early functional recovery.
Low-power laser has been used in several clinical and experimental research studies on peripheral nerve system injuries because it promotes microcirculation stimulus through paralysis of pre-capillary sphincters, induction of arteriolar and capillary vasodilatation, and vascular neoformation, thus leading to an increase in blood flow in the irradiated area. This procedure promotes changes in enzymatic reactions by inhibiting both synthesis of prostaglandins and release of autacoids. Low-power laser has also been employed for healing different types of tissues, because it stimulates the production of adenosine triphosphate (ATP), which enhances the cells' mitotic activity (Karu et al., 1995(Karu et al., , 2004Khullar et al., 1995;Kitchen & Partridge, 1991;Manteifel et al., 1997;Schindl et al., 1999). Several studies using different methodologies to assess the use of low-power laser for treating peripheral nerve system injuries are currently being carried out. The use of different laser models depends on variables such as wavelength (632-904 nm), energy, density, duration, mechanism, type of injury and its treatment. Several parameters, such as wavelength, energy density, laser pulse and potency, have been used to stimulate regeneration and accelerate functional recovery of peripheral nerves Mohammed et al., 2007;Rochkind et al., 1987;Reis et al., 2009;Walsh et al., 2000).
In general, studies on laser therapy using continuous emissions had positive outcomes for peripheral nerve regeneration. However, Bagis et al. (2003) observed no benefit from using low-power laser for nerve injuries.
The interaction between laser and molecules depends on several physical parameters and is evident in the relationship between wavelength and biological response. The activation pathways proposed for low-level laser therapy (LLLT) take into account its action on the chromophores located in the mitochondria and the cell membrane. Red light has a preferred share in the mitochondria and infrared chromophores in the cell membrane (Amat et al., 2006). Therefore, the therapeutic effects are specific, which suggests that there is the possibility of using wavelengths defined with the aim of increasing a particular biological response.
The biological action of laser radiation in the visible region of light, and its clinical application, is based on three reactions: (1) photodynamic action on membranes, accompanied by intracellular calcium increase and cell stimulation; (2) photoreactivation of Cu-Zn superoxide dismutase (SOD); and (3) photolysis of the metal complexes of nitric oxide with release of this vasodilator. It was postulated that these three effects underlie the indirect bactericidal, regenerative, and vasodilatory actions of laser radiation (Vladimirov et al., 2004). It can be considered that the improvement in motor response obtained with a wavelength of 660 nm can be related to the phenomenon of photoreactivation of cellular superoxide dismutase (Cu-Zn-SOD), observed with the helium-neon (He-Ne) laser in wound healing. Radiation of exudates with an He-Ne laser also suppressed luminescence, the laser light thus acting as catalase or superoxide dismutase. It would be natural to suggest that the activity of catalase or superoxide dismutase in exudates was initially reduced under some conditions and that laser radiation reactivated one of those enzymes (Romm et al., 1986). It should be noted that both enzymes absorb at the He-Ne laser wavelength of 633 nm.
Another well studied activity, which might be related to the results, is associated with the production of ATP. In animal cells the sodium-potassium (Na+-K+ gradient controls cell volume, drives the active transport of sugars and amino acids, and renders nerve and muscle cells electrically excitable. The fact that more than one-third of the ATP consumed by an animal at rest is used to operate this pump underscores the importance of this mechanism (Pedersen & Carafoli, 1987). It must be considered that cytochrome-c oxidase is the photoreceptor in the red region of the spectrum and is responsible for activating the synthesis of ATP and, consequently, cell metabolism (Manteifel & Karu, 2005). The ability of the cell to have a greater energy intake during the repair process might be related to the better response observed in the group treated with laser 660 nm, since the mitochondria selectively absorb that wavelength. Visible wavelengths (632.8 nm) are reported to increase the activity of Na+-K+ ATPase in erythrocytes (Kilanczyk et al., 2002). In cells that do have mitochondria, the operation of the Na+-K+ ATPase without ATP due to irradiation in concrete cellular metabolic states will lead to an increase in cellular ATP concentration, and, therefore, ATP synthesis will stop. This hypothesis is supported by the experimental observation that the substance that blocks the Na+-K+ ATPase stops mitochondrial respiration by increasing cellular ATP concentration (Karu et al., 2004). The authors also mention that nitric oxide is associated with stimulation of mitochondria biogenesis, increased microcirculation and apoptosis. Bolognani et al. (1992) found that myosin ATPase previously inactivated by carbon dioxide (CO2) gas could be partially reactivated after irradiation with He-Ne (632.8 nm). In this context, it is suggested that increased mitochondrial ATP might have promoted a more restorative response in the peripheral nerve, thus enabling better functional recovery.
Morphological changes in the mitochondria of lymphocytes were also observed after radiation with red laser, as well as the proliferation of mononuclear cells, responses that might be beneficial in the process of tissue repair (Gulsoy et al., 2006;Karu, 1992).
For all effects presented, the use of low-power laser should be considered in case of injuries of the peripheral nervous system.
Is well known nowadays that physical agents like electricity, magnetic field and ultrasound may positively influence the outcome of the healing process of different tissues like skin, bone, muscles and tendons and peripheral nerves (Brighton, 1981;Mendonça et al., 2003;Pomeranz et al., 1984).
Ultrasound have been studied in the area of enhancing recovery after peripheral nerve injury: 1) reducing pain and improving function with entrapment neuropathies, and 2) facilitating regeneration. Regarding the therapeutic ultrasound, the first investigations were addressed only at the alterations induced in the conduction velocity of the ulnar and radial superficial sensory nerves, with the demonstration that conduction velocity increases or decreases depending on the intensity and period of ultrasound application, a fact attributed to the thermal or mechanical effects of the ultrasound (Farmer, 1986;Halle et al., 1981;Moore et al., 2000). Despite the wide use of therapeutic ultrasound to treat a wide variety of pathologic conditions of the musculoskeletal system, very little is known about its effects upon damaged peripheral nerves. However, some evidence has been produced that peripheral nerves somehow respond to ultrasound irradiation, although the results of previous investigations were somewhat inconclusive, particularly in what refers to the application in humans. Lowdon et al.. (1988) investigated the role of therapeutic ultrasound irradiation in the regeneration of the tibial nerve of rats following a compression lesion, using continuous irradiation (1 MHz, 0.5 and 1 W/cm 2 , 1 min application, three times a week, 2-3 weeks) over the lesion site, and demonstrated that the conduction velocity recovered significantly earlier with the intensity of 0.5 W/cm 2 and significantly later with the intensity of 1 W/cm 2 , as compared to non-irradiated nerves. They concluded that irradiation with low intensity therapeutic ultrasound can improve regeneration of a peripheral nerve with a compressive lesion, but a delayed regeneration can result from high intensity irradiation. A similar effect was demonstrated in rats whose sciatic nerve was submitted to a crush injury at its midportion followed by irradiation with therapeutic ultrasound of different intensity, frequency and duration, applied three times a week for 1 month. Regeneration of the nerve was enhanced with 0.25 W/cm 2 intensity and 2.25MHz frequency (Mourad et al., 2001).
Authors showed that ultrasound intensities as low as 0.5 W/cm 2 w o u l d b e e n o u g h t o accelerate regeneration of the tibial nerve after a limited lesion (moderate compression) in rats but such a low intensity would probably be useless in humans. They also suggested that nerve www.intechopen.com reaction to ultrasound would be different in damaged and intact nerves, the former being more sensitive and susceptible to the induced thermal conduction, probably the actual agent of regeneration. They were unable to suggest any other mechanism of action of the ultrasound.
There are some evidences that regeneration of the peripheral nerves can be accelerated by electric stimulation and a number of experimental studies have shown that the first signs of regeneration begin to appear by the third postoperative week and continue to happen for up to 90 days. Authors are unanimous to state that such low intensity has beneficial effect upon peripheral nerves regeneration. Although neither the intensity suggested nor the material used to make the electrodes vary from one to another. There is a controversy regarding to current intensity. Some authors used a very low current of up to 1.5 mA (Beveridge and Politis, 1988;Kerns et al., 1987Kerns et al., , 1991Politis et al., 1988aPolitis et al., , 1988bPomeranz et al., 1984;Shen and Zhu, 1995), while others used 10 mA (McDevitt et al., 1987;Roman et al., 1987;Pomeranz & Campbell, 1993) or higher (Kerns et al., 1986, with 10 mA/cm 2 ). One study used rat femoral nerve model supported a continuous electrical stimulation proximal to the site of repair for accelerating axonal growth (Al-Majed et al., 2000).

Conclusion
Despite advances in surgical techniques over time, several cellular events and favorable clinical status should be linked and coordinated so that nerve regeneration occurs with success. In clinical practice, it's observed that the recovery of motor and sensory function still represents a challenge to reconstructive surgery and rehabilitation.
Regarding the hand sensation recovery, various sensorial re-education strategies have been introduced in the rehabilitation process with the aim of enhance patient capacity to reinterpret altered sensory stimuli due to injury sustained in the hand.
Rehabilitation is based on exercise therapy, splints and neuroplasticity principles.
This concept aim to facilitate sensory integration with the cortex area and promotes an interaction between tactile, visual and auditive stimuli, therefore represents an important tool in order to optimize sensory re-education strategies and maximize preservation of the hand's cortical map representation in the early phase following injury.
Furthermore, the use of therapeutic modalities for peripheral nerve system regeneration is currently investigated. Low-power laser, ultra-sound, and electric stimulation have been used for accelerating regenerative processes in order to achieve early functional recovery.

Acknowledgment
This project had financial support from the FAEPA -Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Brazil.